Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales

Michael J. Chon, Matthew Daly, Bin Wang, Xianghui Xiao, Alireza Zaheri, Marc A. Meyers, Horacio D. Espinosa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Pangolin scales form a durable armor whose hierarchical structure offers an avenue towards high performance bio-inspired materials design. In this study, the fracture resistance of African pangolin scales is examined using single edge crack three-point bend fracture testing in order to understand toughening mechanisms arising from the structures of natural mammalian armors. In these mechanical tests, the influence of material orientation and hydration level are examined. The fracture experiments reveal an exceptional fracture resistance due to crack deflection induced by the internal spatial orientation of lamellae. An order of magnitude increase in the measured fracture resistance due to scale hydration, reaching up to ~ 25 kJ/m2 was measured. Post-mortem analysis of the fracture samples was performed using a combination of optical and electron microscopy, and X-ray computerized tomography. Interestingly, the crack profile morphologies are observed to follow paths outlined by the keratinous lamellae structure of the pangolin scale. Most notably, the inherent structure of pangolin scales offers a pathway for crack deflection and fracture toughening. The results of this study are expected to be useful as design principles for high performance biomimetic applications.

Original languageEnglish (US)
Pages (from-to)30-37
Number of pages8
JournalJournal of the Mechanical Behavior of Biomedical Materials
Volume76
DOIs
StatePublished - Dec 2017

Keywords

  • Bio-inspired design principles
  • Biomaterials
  • Fracture toughness
  • Hierarchical structure
  • Pangolin scale

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering
  • Mechanics of Materials

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